> Now if I include recordtype
> = "custom" in marc_local.properties file then how it can trigger my
> custom record driver in ../RecordDriver/ directory? Where should I make
> that change?

If the recordtype field in your index is set to custom, VuFind will look
for a record driver file named CustomRecord.php in the RecordDriver
directory. In that file it expects a php class called CustomRecord, that
implements RecordInterface.
The selection of the record driver to load is made in
RecordDriver/Factory.php.

If I understand correctly, you want to suppress item status lookup in
the ILS for certain records and these records are in MARC format. So you
may simply want to extend the MarcRecord class and only change the line
$interface->assign('summAjaxStatus', true); to
$interface->assign('summAjaxStatus', false); in the method
getSearchResult().
So your CustomRecord.php might be as simple as

// custom records are MARC records, but have no holding/status
// data in the ILS. So set summAjaxStatus to false to suppress
// AJAX calls to the ILS when record is displayed as MARC record
$template = parent::getSearchResult();
$interface->assign('summAjaxStatus', false);
return $template;
}